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Page 6 · DO #4219 · 182_Goodspeed_Bx3FF59_r
- Collection
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Thomas Harper Goodspeed (1887–1966) papers
- Item/Folder
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Nicotiana Phylesis, undated
- Digital Object
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DO #4219,
page 6
- Collection-level dates
- 1923–1963
Page transcription
b) Chromosome number and particular chromosome morphology has been determined in all of the fifty-five species available and in an equal number of varieties. Investigation of chromosome morphology on a comparative basis has been made from metaphase of first division in pollen grains — and it is no mean feat to secure superior preparations of pollen grain divisions in nearly sixty different species.
The following chromosome numbers are characteristic of Nicetiana species.
American: 9 (3 species), 10 (2), 12 (28), 24 (9)
Australasian and South Pacific: 16 (4), 18 (1), 19 (2), 20 (2), 21 (1), 22 (1), 24 (2)
Tobac: 9 (3), 10 (2), 12 (28), 16 (4), 18 (1), 19 (2), 20 (2), 21 (1), 22 (1), 24 (1)
c) Orietic chromosome behavior has been studied particularly in many of the species and in a large number of F, interspecific hybrids.
1) In the case of species A the relation of chromosome size and morphology to choma frequency and terminalization, and the resulting MI bivalent configurations have been studied. determined.
2) We have studied extent and quality of pairing in 133 F, interspecific hybrids and the results of others investigations have added data on T8 additional F, hybrids. In the case of the 133 F, hybrids our study has involved analyses of pairing in from 50 to 100 PNC by two investigators working independently. The totals of 211